1. Field of the Invention
The present invention relates to a recording ink which is suitable for inkjet recording, as well as an ink media set, an ink cartridge, an ink record, an inkjet recording apparatus and an inkjet recording method using the recording ink.
2. Description of the Related Art
An inkjet recording method is the method to perform printing by ejecting small liquid drops of an ink to adhere onto a recording medium such as paper. As the ink used for this inkjet recording method, those in which colorants of various dyes and pigments have been dissolved or dispersed in water or water and an organic solvent having a high boiling point and a wetting agent composed of the organic solvent having the high boiling point has been abundantly contained for keeping a moisturizing property are used. Such a wetting agent composed of the organic solvent having the high boiling point contributes to preventing nozzles from being dried by its water-holding capacity. However, when printing on the paper with a rapid penetrating speed, e.g., plain paper, there is a shortcoming that show-through is increased because the wetting agent is hardly evaporated.
Meanwhile, on the papers such as non-porous substrates such as offset coated papers for printing, plastic films, plastic laminate papers and plastic coated papers which have a low water-absorbing capacity, it takes a long time for drying because the wetting agent is hardly evaporated, which is impractical.
Thus, it is desired to provide an inkjet recording method in which drying is rapid on the paper for printing, an image density is high, an image quality is high on the plain paper and no clogging occurs when stopped for a long time.
For example, in Japanese Patent Application Laid-Open (JP-A) No. 2004-115551 an inkjet ink in which a content of the wetting agent has been excessively low is proposed. According to this proposal, even when the plain paper is used, the image quality with no show through having the high image density is obtained. However, in this proposal, since no resin is contained in the ink, a fixing property of the image is inferior particularly when a pigment ink is used. Enhancement of a drying speed when printed on the offset coated paper is neither disclosed nor suggested.
In JP-A No. 60-34992, quick drying inks are proposed. However, in Example in this proposal, the wetting agent is abundantly contained at 15% by mass or more, no resin is added and quality papers are used as the paper. Thus, coated papers for printing which extremely hardly absorb the water do not subject to this proposal.
In JP-A No. 08-109343, quick drying inks for the inkjet of a current-carrying heat generation system are proposed. However, in this proposal, no resin is added, electrolytes are considerably abundantly contained, the fixing property of the image is inferior, and an ejecting system which is essentially different from the inkjet of a piezoelectric system is employed.
In JP-A No. 2002-67473 and JP-A No. 2002-69346, a combination of microcapsule type pigments with the paper for printing is proposed. However, in these proposals, heating by microwave is required for enhancing a drying property because of a usual ink composition.
In JP-A No. 2002-301857 containing wax fine particles and resin fine particles are proposed. In this proposal, the wax fine particle is used in place of the wetting agent because it can impart a wetting property. However, the wax having the wetting property tends to be inferior in fixing property and drying.
In JP-A No. 06-171072, inks containing a resin emulsion, a polymer dispersant and a pigment are proposed. In the ink in this proposal, since the wetting agent content is low but a concentration of an entire solid content is low, there are problems in that the sufficient image density and color formation are not obtained.
In JP-A No. 2003-226827, the ink containing a fluorine surfactant and a polymer emulsion containing a water-insoluble or water-hardly soluble color material in polymer fine particles, whose viscosity is 5 mPa·s or more is described. However, it is not described to record on non-porous medium such as plastic films.
When printed on an unabsorbable recording medium such as polyester films, generally the ultraviolet ray curable ink is used because the usual ink is inferior in fixing property and drying property (see JP-A No. 2000-117960). However, since strong ultraviolet light is required and the apparatus is grown in size due to storage stability of the ink, the apparatus is not common as a printer.
Meanwhile, the methods of enhancing the drying property and the fixing property by oil-based inks are available, but the solvent is the organic solvent, and thus, they can not be generally used in places such as offices where odor is avoided.
As water-based inks used for printing on polyolefin films, those containing the resin at high concentration are proposed, for example, in JP-A No. 04-139271. However, it is not described whether the ink can be used as the inkjet ink.
In JP-A No. 2005-15672, a non-water-based inkjet ink for polyvinyl chloride resin sheets is proposed. This proposal is the non-water-based ink, and is not suitable for the use in the office in terms of environmental problem such as odor.
Also, the inkjet ink printed on the non-porous substrate such as vinyl medium is described in JP-A No. 2005-220352. So far as this is seen in Example, the concentration of the total solid content is 6% by mass and the amount of the wetting agent is 21% by mass. When the solid content is low in this way, the amount of the wetting agent is large and the amount of the adhered ink having the relatively low viscosity is large per unit area, unevenness of the image density due to liquid flow referred to as beading and liquid bias easily occurs particularly in solid images.
In JP-A No. 2000-44858, the inkjet ink printed on the vinyl medium is proposed, and dried at 70° C. in this Example. When seen in Examples, the amount of wetting agent in the ink is large, the solid content is low which is 10% by mass or less, and thus it is speculated that the drying is necessarily slow and no good image is obtained unless drying is performed by heating. That is, in the [ink sample 1] described in the above JP-A No. 2000-44858, when calculated, the solid content is 11% by mass which is more than 10% by mass, but the resin includes a dispersant polymer and is not an emulsion type. Thus it is speculated that the resin in a large amount can not be added.
Therefore, it is an actual circumstance that a recording ink and an inkjet recording method having sufficiently satisfied performances are not obtained yet, i.e., the ink for printing by which the image having a high image density, a low backside density, good color formation and no bleeding is obtained when printed on the plain paper and the sharp image close to printed matters, having no problem in drying speed is obtained on smooth papers for printing having a low water absorbing capacity and non-porous substrates such as plastic films, plastic laminate papers and plastic coated papers, and the inkjet recording method using the recording ink, where no clogging of nozzles occurs when stopped for a long time are not obtained yet.